Psilocybe cubensis spore morphology: shape, size, wall and germ pore under the microscope

01The reference description

• Shape: subellipsoid, sometimes described as ovoid or slightly flattened on one side. Not lemon-shaped (that is Panaeolus).
• Size: typically 11 to 17 micrometres long and 7 to 10 wide. A population from one print clusters in the middle of that range.
• Wall: thick and smooth, clearly visible as a band at 1000x.
• Germ pore: a small, thinner, flattened area at one end, visible at 1000x and sometimes at 400x with good contrast.
• Colour: purple-brown individually under transmitted light; deep purple-brown to nearly black in a dense print.

02What varies between strains

Pigment varies most. Albino lines (APE, Jack Frost, ABV, True Albino Teacher) carry spores of the same shape and size with almost no colour, so they read as glassy outlines. Leucistic lines are pale in the fruiting body but usually keep pigmented spores. Size range varies with isolation: an isolate's population is tight, a multispore or wild line spreads wider. Deposit density varies with the line's spore output: Penis Envy family lines print thinly.

What does not vary much is shape and the germ pore. A cubensis spore from any strain is recognisably the same object, which is why differences between lines have to be measured rather than eyeballed.

03Telling it from its neighbours

• Panaeolus cyanescens: black in mass, opaque, lemon-shaped, slightly larger.
• Ochra (Psilocybe ochraceocentrata): very close to cubensis on the slide; the print is lighter and browner. Measure and print rather than guess.
• Gourmet species (oyster, lion's mane): much smaller, colourless to pale, and white to lilac in mass. Unmistakable next to a cubensis drop.

04Recording a population

1. Calibrate the graticule against a stage micrometer for the objective you use.
2. Measure twenty spores from different parts of the field, length and width.
3. Record the range and the median, not a single value.
4. Note wall, germ pore, pigment and the print colour if you have one.
5. Write the strain and LOT at the top. Without them the numbers are orphaned.

Do this for a Golden Teacher and a DreadMaw and an APE and you will have, in three pages, a better feel for cubensis variation than any description can give.